Despite delays and setbacks, the spacecraft intended to become first commercial vehicles to dock with the International Space Station (ISS) are making good progress on their way to launch. SpaceX and Orbital Sciences, the two companies awarded contracts under the commercial orbital transportation services (COTS) contract, are making significant progress on the issues that have led both to delay landmark launches.
SpaceX, initially scheduled to dock the Dragon capsule with ISS in February, cancelled the launch over software testing and electromagnetic interference (EMI) concerns. Testing shortly before the flight revealed that some transducers may have been subject to interference from transmitters aboard ISS. The problem has largely been solved, according to sources with knowledge of the issue.
"The big thing we're working on is software. We're just making sure that every 'I' is dotted and every 't' is crossed, and a big part of that is making sure the software is ready to go," said Garrett Reisman, senior engineer for astronaut safety at SpaceX.
"We're looking at the end of April. We'll launch when we're ready, when the vehicle is ready," he added.
©Orbital Sciences
The Dragon capsule will be equipped with Super Draco abort engines in case of emergency. The first Super Draco firing occurred in January, and the engine has undergone 17 full-burn tests to date.
Orbital Sciences was forced to delay the first flight of its Antares launch vehicle due to construction delays with its Mid-Atlantic Regional Spaceport (MARS) launch pad at Wallops Island, Virginia.
Since the Virginia Department of Transportation took over administration of the facility in late 2011, construction has sped up significantly, but the launch pad is not ready for use.
"They actually know how to build big things, they know how to bring in construction teams, they know how to work around the clock," said Frank Culbertson, senior vice president at Orbital Sciences' advanced project group.
"We expect to have the pad turned over to us within two months, and from there it'll be ours to start a hot-fire and a first test flight, then start operational missions," he added.
The hot-fire test is now scheduled for May, 2012, and the Antares flight scheduled for June. Antares cores have been completed and stored.
Antares will launch with a simulated Cygnus capsule. Four of the Cygnus capsules, which will carry supplies to the ISS, are in various stages of production. The first Cygnus was inserted into a thermal vacuum chamber on 15 February, where the capsule will spend two weeks in a simulated space environment.
Zach Rosenberg, Flight Global